Intergrated channel plate and decoupler assembly for vibration isolator

ABSTRACT

An integrated plate assembly and method for forming an engine mount assembly comprises a unitary molded plate having an elongated fluid channel communicating between first and second sides of the plate. A cavity formed therein communicates with the first and second sides of the plate. The cavity receives a decoupling member having first and second surface areas facing outwardly toward the first and second sides of the plate.

BACKGROUND OF THE INVENTION

This application claims the priority benefit of and hereby expresslyincorporates by reference U.S. provisional application Ser. No.60/354,160, filed Feb. 4, 2002.

This application relates to a vibration isolator, and more particularlyto an integrated channel plate and decoupler assembly used in avibration isolator.

Vibration isolators or engine mounts are well known in the automotiveindustry for controlling or attenuating vibrations related to engineand/or road conditions. Typically, the vibration isolator is a fluidfilled assembly mounted, for example, between an engine and a vehicleframe. First and second chambers of the isolator are separated by achannel plate that has an elongated channel providing fluidcommunication between the chambers. The channel allows fluid tooscillate between the chambers and provides a desired dynamic stiffnessin response to a selective range of frequencies. For example, largeamplitude and low frequency vibrations are effectively dampened and thedesired stiffness is provided as a result of the fluid passing throughthe elongated channel. It is also known in the art, for example as shownand described in U.S. Pat. Nos. 4,720,086 and 4,889,325, to use adecoupling means to selectively inactivate or decouple the elongatedchannel at selected amplitudes and frequencies. Typically, thedecoupling means includes a diaphragm or disk (decoupler) that controlsfluid flow through an associated passage by oscillating in response tohigh frequency, low amplitude vibrations. At a certainamplitude/frequency the decoupler engages a seat and thus blocks flowthrough the associated passage and thereby requiring fluid to flowbetween the chambers through the elongated channel. Thus as is known inthe art, small amplitude, high frequency vibrations require a lowstiffness to filter these vibrations. The decoupler or decoupling meansachieves this operation. On the other hand, larger amplitude and lowerfrequency vibrations require an increased stiffness. Accordingly, thedecoupler forces the fluid to pass through the elongated channel toachieve this dampening function.

As will be appreciated, the channel plate, decoupler/high frequencywasher are typically separate components. This adds to manufacturing andassembly costs. Thus, a need exists to reduce the number of componentsby integrating them into a single assembly in order to simplify theassembly and reduce costs associated with the manufacture and assemblyof vibration isolators or engine mounts.

SUMMARY OF INVENTION

An integrated plate assembly for use in a yieldable support assemblysuch as a hydraulic engine mount or vibration isolator includes a moldedplate having an elongated fluid channel communicating between first andsecond sides, and a cavity formed in the plate, also in communicationwith the first and second sides of the plate. A decoupling member isreceived and integrally molded in the cavity.

The decoupling member in a preferred embodiment is an elastomeric memberthat deflects in response to forces imposed thereon.

The elongated fluid channel extends at least one revolution about theplate.

In a preferred arrangement, the fluid channel extends approximatelyseven hundred twenty degrees (720°) around the perimeter of the plate.

A method of forming a vibration isolating assembly comprises the stepsof inserting a decoupler into a mold and introducing a polymer into themold around the decoupler to form a plate that fixes the decoupler inthree orthogonal axes relative to the plate.

The method includes the further step of introducing a cured elastomerdecoupler into the mold.

The method includes the additional step of forming a perimeter channelin the plate.

The primary advantage of the invention is the reduction of the number ofcomponents in the assembly.

Still another advantage is the ability to reduce the cost associatedwith the assembly.

Still other advantages and benefits of the invention will becomeapparent to those skilled in the art upon reading and understanding thefollowing detailed description.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal cross-section of an engine mount assembly orvibration isolator of the general type used to dampen vibrations.

FIG. 2 is a digital photograph of a prototype integrated plate assemblyfor use in an engine mount.

FIG. 3 is a plan view of a first or upper surface of the plate assembly.

FIG. 4 is an elevational view of the integrated plate assembly.

FIG. 5 is a bottom plan view of the integrated plate assembly.

FIG. 6 is a cross-sectional view generally along the lines 6-6 of FIG.3.

FIG. 7 is a sectional view taken generally along the lines 7-7 of FIG.4.

FIG. 8 is a sectional view taken generally along the lines 8-8 of FIG.3.

FIG. 9 is a sectional view taken generally along the lines 9-9 of FIG.4.

FIG. 10 is a sectional view taken generally along the lines 10-10 ofFIG. 3.

FIG. 11 is a sectional view taken generally along the lines 11-11 ofFIG. 3.

FIG. 12 is a graphical representation of the damping characteristics ofthe vibration isolator plotting dynamic stiffness (Newtons permillimeter) relative to the frequency (Hertz).

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 generally illustrates a vibration isolator or dampening assembly,also referred to as a hydraulic engine mount assembly such as used in anautomotive vehicle. As is known in the art, the engine mount assembly 20includes a first housing portion 22 having a first or upper chamber 24and a second or lower chamber 26 separated by a channel plate 28. Afluid such as a hydraulic fluid comprised of, for example, propyleneglycol or a mixture of ethylene glycol and water, fills the chambers.The chambers are interconnected via a channel or passageway 30 providedin the channel plate. As is conventional in the art, the channel is anarcuate passage that is also referred to as an inertia track passagewaythat impacts on the resonant frequency of the fluid in the mountassembly. Typically, the channel has a substantially uniformcross-section throughout its entire length and is normally disposedalong or adjacent an outer periphery of the plate with multiple windingsto maximize the length of the channel. Oscillating movement imposed onthe upper portion of the housing is dampened through fluid movement fromthe upper chamber, through the channel, and into the lower chamber whichis enclosed by a flexible wall 32. The oscillation of the fluid in thechannel between the first and second chamber provides the desireddynamic stiffness of the mount assembly. Details of the assembly of FIG.1 are generally conventional and understood by one skilled in the art sothat further discussion herein is deemed unnecessary.

As noted above, it is desirable to selectively decouple or deactivatethe channel during certain frequencies/amplitudes of vibrations. This isachieved through use of a decoupling means, decoupling member, ordecoupler 40 (not shown in FIG. 1) incorporated into the presentinvention as shown in FIGS. 2-11. More specifically, the prior artsuggests that the decoupling means is preferably an elastomeric memberor disk, and on occasion the decoupling means includes a cage containinga particulate matter that selectively blocks and allows fluid flow tothe inertia channel. As shown in FIG. 2, decoupler 40 is an elastomericdisk that is integrally molded in polymeric channel plate 42. Thisconstruction offers a number of advantages over the prior artarrangement.

More particularly, the channel plate is a polymeric or plasticconstruction having a first or upper surface 44 (FIG. 3) and an opposedsecond or lower surface 46 (FIG. 5). An outer peripheral portion 48 ofthe plate includes a continuous channel, groove, or passage that servesas the inertia passageway 50 in the plate (FIG. 4). As is evident inFIG. 3, a first end of the channel communicates with or forms an opening52 in the upper surface of the plate that is in fluid communication withthe upper chamber 24. Likewise, a second end communicates with or formsan opening 54 in the lower surface 46 of the plate to provide fluidcommunication with the lower chamber 26 of the assembly. The channelextends approximately seven hundred and twenty degrees (720°) in itsperipheral path about the plate, although it will be appreciated thatother channel lengths can be used without departing from the scope andintent of the invention. The channel is provided by channel forming wall56 that extends approximately mid-height between the upper and lowersurfaces around a substantial perimeter of the plate and dividing theperimeter into a first/upper flight 50 a and a second or lower flight 50b. Although only two flights are illustrated, it will be appreciatedthat the channel may include a greater or lesser number to respectivelyincrease or decrease the length of the channel as required for aparticular application. With reference to FIG. 4, the dividing wall 56includes a first angled portion 58 that merges into the upper surface 44of the plate at a circumferential position located adjacent the opening52. Additionally, a second angled portion 60 merges from the dividingwall into the lower surface 46 of the plate adjacent the opening 52therein. In this manner, fluid from the upper chamber proceeds throughopening, then travels approximately three hundred and sixty degrees(360°) in the upper flight 50 a of the channel then proceeds between theangled portions 58, 60, through another three hundred and sixty degree(360°) traverse on the lower flight 50 b, and through the opening 54 inthe bottom surface of the plate. In this manner, and under selectedamplitude and frequency of vibration, the upper and lower chamberscommunicate through the inertial passage or channel.

Integrally molded into the plate is the decoupling means or decoupler40. As shown throughout FIGS. 2-11, the decoupling means of the presentinvention is preferably an elastomeric disk. It is encased within thepolymeric channel plate by integrally molding the cured decoupler in acavity 70 adjacent the upper surface 44 of the plate. The cavity 70 issubstantially identical in dimension and volume to that of theelastomeric member. This is achieved in the following manner. A smalldiameter opening 72 is preferably formed in the decoupler. This openingallows the decoupler to be held in place within a mold cavity (notshown) on a similarly dimensioned pin (not shown) and held within themold cavity in a desired spatial relationship relative to the moldwalls. Polymeric material that when cured forms the channel plate isintroduced into the mold cavity and around the decoupler. Once thepolymer is cured, the decoupler is held or maintained in fixed relationrelative to the plate in three orthogonal, axial directions. A matinglylocated opening 74 is formed in a recess portion 76 of the lower surface46 of the plate. As will be appreciated, the openings 72, 74 are axiallyaligned and representative of the location of the pin which holds thedecoupler in position during molding of the channel plate therearound.Once the polymer is sufficiently cured, the pin is axially removed, thusleaving the voids or openings 72, 74. The upper surface of thedecoupler, on the other hand, is restrained from axial movement via acruciform pattern 78 formed in the channel plate (FIG. 3). Four enlargedquadrants 80 a, 80 b, 80 c, 80 d, are formed between the cruciformpattern and expose a substantial surface area of the upper surface ofthe decoupler to the fluid in the upper chamber 24. Similarly, asillustrated in FIG. 5, a cruciform pattern 82 defines four enlargedopenings or lobes 84 a, 84 b, 84 c, 84 d so that a lower surface of thedecoupler is exposed to fluid pressure in the lower chamber 26. It willbe appreciated that the pattern of the plate holding the decoupler infixed relation thereto may be varied from the cruciform relation asshown.

Thus, integrating the decoupler with an inertia channel allows themounting assembly to provide dynamic stiffness in response to both smallamplitudes of vibration and typically high frequency, as well as largeamplitudes typically at a low frequency. The small amplitude/highfrequency vibrations are handled by the elastic nature of the decoupler,while the large amplitude/low frequency vibrations are dampened throughthe inertia channel.

As illustrated in FIG. 12, at low frequencies, the inertia channel isdecoupled and fluid oscillates through the channel between the upper andlower chambers. As the oscillation frequencies increase, however, thedecoupler dampens the vibrations as a result of the elastic nature ofthe decoupler.

According to the preferred method of assembly, the decoupler is insertedand held in fixed relationship in the mold. The polymer of the channelplate is then introduced into the mold around the decoupler and fixesthe decoupler in three orthogonal axes relative to the plate. Once thepolymer is cured, the pin is removed from the decoupler. As will beappreciated, the decoupler is inserted into the mold preferably as acured elastomer material and the polymer used to form the channel plateforms the perimeter channel or passage in the plate as a result of theinner wall configuration of the mold.

An integrated channel plate assembly thus forms the combined componentsof the channel plate and decoupler/high frequency washer into onecomponent. The integration is preferably achieved by molding the polymeraround an inserted rubber disk. The polymer is molded into the shape ofa channel plate with the rubber decoupler disk captured in place by thesurrounding polymer and by the mold core. By designing the part so thatthe rubber disk is encased in polymer around its outer diameter and in acrossing pattern on the top and bottom, the disk is held in place. Theremaining surface area of the rubber disk is not covered with polymerand thereby allows a large surface area to be exposed to the fluid.During operation, the decoupler disk flexes as a result of the pressureof the fluid resulting in a lower dynamic stiffness, i.e., function ofdecoupling. The functionality of separate components as used in theprior art is achieved with this integrated component.

The invention has been described with reference to the preferredembodiment and method. Obviously, modifications and alterations willoccur to others upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations.

1. An integrated plate assembly for use in a yieldable support, theassembly comprising: a unitary, molded plate having first and secondsides, and an elongated fluid path communicating between the first andsecond sides, and a cavity formed in the plate communicating with thefirst and second sides of the plate; and a decoupling member received inthe cavity and having first and second surfaces facing outwardly towardthe first and second sides of the plate, respectively.
 2. The assemblyof claim 1 wherein the decoupling member is sealingly received in thecavity to preclude fluid communication of the first side with the secondside of the plate through the cavity.
 3. The assembly of claim 2 whereinthe decoupling member is partially supported along the first and secondsurfaces by the plate whereby the decoupling member deflects in responseto forces imposed thereon.
 4. The assembly of claim 3 wherein thedecoupling member is an elastomeric member that elastically deflects inresponse to the forces imposed thereon.
 5. The assembly of claim 2wherein the plate includes support members extending across portions ofthe first and second surfaces of the flexible member to encase theflexible member in the plate and allow limited deflection alongunsupported regions of the surfaces.
 6. The assembly of claim 1 whereinthe elongated fluid path includes a generally circumferentiallyextending channel.
 7. The assembly of claim 6 wherein thecircumferentially channel extends at least one revolution about theplate.
 8. The assembly of claim 1 wherein the flexible member is formedfrom a resilient material.
 9. The assembly of claim 8 wherein theflexible member is formed of rubber.
 10. The assembly of claim 1 whereinthe plate is formed of a rigid plastic.
 11. The assembly of claim 1wherein the elongated fluid path extends about a periphery of theflexible member.
 12. A vibration isolating assembly adapted for use inan engine mount that includes a housing having first and second fluidchambers in selective communication with one another, the vibrationisolating assembly comprising: an integrally molded plate having acavity enclosing a decoupler, the plate having a passage thatcommunicates with the first fluid chamber at a first end and with thesecond fluid chamber at a second end whereby fluid is displaced from oneof the fluid chambers to the other, and the decoupler encased within theplate with substantial first and second surface portions thereof exposedto the first and second fluid chambers, respectively.
 13. The vibrationisolating assembly of claim 12 wherein the decoupler is a resilientmaterial.
 14. The vibration isolating assembly of claim 12 wherein thepassage includes a serpentine passage.
 15. The vibration isolatingassembly of claim 12 wherein the passage includes a peripheral channelformed in the molded plate.
 16. The vibration isolating assembly ofclaim 15 wherein the passage extends greater than three hundred sixtydegrees (360°) around the perimeter of the molded plate.
 17. Thevibration isolating assembly of claim 15 wherein the passage extendsapproximately seven hundred twenty degrees (720°) around the perimeterof the molded plate.
 18. A method of forming a vibration isolatingassembly comprising the steps of: inserting a decoupler into a mold;introducing a polymer into the mold around the decoupler to form a platethat fixes the decoupler in three orthogonal axes relative to the plate.19. The method of claim 18 wherein the decoupler is a cured elastomermaterial before inserting into the mold.
 20. The method of claim 18wherein the polymer introducing step includes the step of forming aperimeter passage in the plate that communicates with first and secondsides thereof.